Methods: Clinically stable lipoatrophic HIV-infected patients receiving antiretroviral therapy containing stavudine 40 mg bid with a plasma HIV RNA <200 copies/mL for at least 6 months were randomized to maintain stavudine 40 mg bid (d4T40 arm), to reduce to 30 mg bid (d4T30 arm), or to switch from stavudine to tenofovir-DF (TDF arm) while preserving the remaining drugs. Fasting metabolic parameters were assessed at baseline and at weeks 4, 12, and 24. Mitochondrial parameters in peripheral blood mononuclear cells and body composition were measured at baseline and at week 24.